The life support systems currently used by US Air Force fighter aircrew are a combination of apparatuses that include an anti-gravity suit (which provides counterpressure to the aircrew's lower body thus preventing pooling of blood in the lower body, one of the adverse effects of sustained acceleration), a counterpressure vest (which inflates to apply pressure to the aircrew's chest and back thus helping the heart pump blood up to the eyes and brain, inhibiting downward blood flow), a high pressure oxygen mask (which delivers breathing gas to the aircrew) and a helmet with a bladder (which inflates to tighten the mask straps to keep the aircrew's oxygen mask in position and ensure a good seal). To reduce the thermal burden on the aircrew resulting from all of these components, the aircrew may also wear a cooling vest.
A breathing gas terminal block worn on the aircrew's combat flight uniform acts as a connector between manside components and aircraft equipment.
Aircraft equipment typically includes an anti-gravity valve and breathing regulator. When the anti-gravity valve senses increasing pressure beyond the operational threshold level, it pressurizes the aircrew's anti-gravity suit and sends a signal to the breathing regulator, which increases the pressure of the oxygen-enriched breathing gas distributed by the terminal block to the oxygen mask, helmet bladder and counterpressure vest. The breathing regulator receives oxygen-enriched breathing gas from a main breathing gas supply on the aircraft, such as an on board oxygen generating system (OBOGS). Also included with aircraft equipment is an aircraft mounted filter/blower which directs gas to the cooling vest.
Although this life support system provides fighter aircraft aircrew with high gravity protection (known in the art as PBG, or pressure breathing for acceleration protection), and some thermal relief, it provides no environmental defense protection. It would therefore be desirable to integrate environmental (biological/chemical) defense protection with pressure breathing capability and body cooling into a single life support system.
Chemical defense protection for aircrew is typically provided by an impermeable butyl rubber hood to which a visor and oxygen mask are integrally attached. The impermeable hood assembly is worn under the aircrew's helmet. The hood assembly provides chemical defense protection for the aircrew both in the air and on the ground (that is, when the aircrew is going to and from the aircraft). Although the hood assembly provides the aircrew with protection from chemical contaminants, its use can result in problems relating to sweat buildup under the hood, which is uncomfortable for the aircrew, and misting of the hood visor, which diminishes the aircrew's vision. Such demisting/fogging problems are common in most substantially closed environments incorporating visual systems and/or eye protection (e.g., visors, goggles, glasses, etc.). In addition, as previously indicated, chemical and biological defense protection is not currently integrated with pressure breathing capability into one fighter aircraft aircrew life support system.
It would therefore also be desirable to provide demisting capabilities for visual apparatuses, and to provide such capabilities for incorporation into environmental defense and/or antigravity life support systems.
It is therefore a feature of the present invention to provide a life support system which provides chemical defense and high gravity protection for the aircrew of a high performance fighter aircraft. A further feature of the present invention is to incorporate in an aircrew acceleration life support system a chemical defense hood assembly which provides chemical defense protection for the aircrew in the air and on the ground. A further object of the present invention is to provide a life support system which includes the capability to demist the aircrew's visor and cool the aircrew's head and body.
It is an advantage of the present invention that it is usable with the main source of breathing gas on the aircraft (such as an on board oxygen generation system or OBOGS), an aircraft-mounted filter/blower, and a portable filter/blower. A further advantage of the present invention is that it enables the aircrew to obtain demist gas from the OBOGS in the event of filter/blower failure. A further advantage of the present invention is that it enables the aircrew to manually control the source of demist gas.
Other aspects and advantages of the invention are set forth in part herein and in part will be obvious herefrom, or may be attained by means of instrumentalities and combinations pointed out in the appended claims.